linux+ guide to linux certification, second edition
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Linux+ Guide to Linux Certification, Second Edition. Chapter 9 System Initialization and X Windows. Objectives. Summarize the major steps necessary to boot a Linux system Configure the LILO and GRUB boot loaders Dual boot Linux with the Windows OS using LILO, GRUB, and NTLOADER - PowerPoint PPT PresentationTRANSCRIPT
Linux+ Guide to Linux Certification, Second Edition
Chapter 9System Initialization
and X Windows
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Objectives
• Summarize the major steps necessary to boot a Linux system
• Configure the LILO and GRUB boot loaders
• Dual boot Linux with the Windows OS using LILO, GRUB, and NTLOADER
• Understand how the init daemon initializes the system at boot time into different runlevels
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Objectives (continued)
• Configure the system to start daemons upon system startup
• Explain the purpose of the major Linux GUI components: X Windows, Window Manager, and desktop environment
• List common Window Managers and desktop environments used in Linux
• Configure X Windows settings using various Linux utilities
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The Boot Process
• POST: Series of tests run when computer is turned on – Ensures functionality of hardware
• MBR: Defines partitions and boot loader – Normally located on first HDD sector
• Boot loader: Program used to load an OS• MBR might contain pointer to a partition containing
a boot loader on the first sector• Active partition: Partition pointed to by MBR
– One per HDD
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The Boot Process (continued)
• /boot: Directory containing kernel and boot-related files
• Vmlinuz-<kernel version>: Linux kernel file• Daemon: System process that performs useful
tasks– e.g., printing, scheduling, OS maintenance
• Init (initialize) daemon: First process started by Linux kernel– Loads all other daemons– Brings system to usable state
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The Boot Process (continued)
Figure 9-1: The boot process
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Boot Loaders
• Primary function: Load Linux kernel into memory
• Other functions:– Passing information to kernel– Booting another OS
• Two most common boot loaders:– Linux Loader (LILO)– GRand Unified Boot loader (GRUB)
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LILO
• Traditional Linux boot loader
• Typically located on MBR
• Allows choice of OS to load at startup
• To configure, edit /etc/lilo.conf
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LILO (continued)
• append= keyword (in /etc/lilo.conf): Useful for manually passing information to Linux kernel– Can pass almost any hardware information
• Format is hardware dependent
• Must reinstall LILO if /etc/lilo.conf file altered
• lilo command: Reinstalls LILO– -u option: Uninstall LILO
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GRUB• More recent than the LILO boot loader• Stage 1: First major part of GRUB
– Typically resides on MBR– Points to Stage 1.5
• Stage1.5: Loads filesystem support– Resides in /boot/grub
• Stage2: Performs boot loader functions – Displays graphical boot loader screen
• To configure, edit /boot/grub/grub.conf– Read directly by Stage 2 boot loader– HDDs and partitions identified by numbers
• Format: (hd<drive#>,<partition#>)
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GRUB (continued)
Figure 9-3: GRUB boot loader screen
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GRUB (continued)
• GRUB root partition: Partition containing Stage 2 boot loader and grub.conf file
• GRUB normally allows manipulation of boot loader– To prevent, enable password protection
• grub-md5-crypt command: Generates encrypted password for use in grub.conf file
• Can switch boot loader from GRUB to LILO at any time
• grub-install command: Installs GRUB boot loader
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GRUB (continued)
Figure 9-4: Viewing help at the GRUB boot loader screen prompt
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Dual Booting Linux
• Only one OS may be used at a time
• Boot loader may be configured to allow choice of OS at boot time
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Using LILO or GRUB to Dual Boot other Operating Systems
• Dual boot: Two or more OSs exist on HDD
• Easiest if Linux installed after another OS– Allows installation program to detect other OS
• Place appropriate entries in boot loader configuration file
• LILO and GRUB cannot load Windows Kernel directly
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Using LILO or GRUB to Dual Boot other Operating Systems (continued)
Figure 9-5: Partitioning for a dual boot system
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Using LILO or GRUB to Dual Boot other Operating Systems (continued)
Figure 9-6: Configuring GRUB for a dual boot system
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Using FIPS
• Windows installers use entire HDD for Windows partitions– Leaves no space for Linux
• First non-destructive Interactive Partition Splitter (FIPS): Resizes Windows partition – Preserves Windows OS on Windows partition – Creates space to install Linux
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Using FIPS (continued)
• Guidelines/limitations to using FIPS:– FAT16 and FAT32 filesystems only– Will only work with primary Windows partition – Windows partition split into two primary partitions– Need sufficient free space within existing Windows
partition to allow Linux installation
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Using a Windows Boot Loader to Dual Boot Linux
• Specify location of GRUB or LILO in Windows boot loader configuration
• NTLOADER: Boot loader available with Windows NT/2000/XP– At boot time, prompts for OS to boot– Able to load LILO or GRUB
• Windows must be installed on first primary active partition– NTLOADER placed on MBR by default
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Using a Windows Boot Loader to Dual Boot Linux (continued)
Figure 9-7: Configuring GRUB to reside on a Linux partition
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Using a Windows Boot Loader to Dual Boot Linux (continued)
• When Linux installed, install GRUB on first sector of the partition– Avoids overwriting NTLOADER in MBR
• After Linux installed: – Run Linux rescue utility– Make GRUB bootable image file (linboot.bin)– Reboot into Windows OS– Copy linboot.bin to C:\– Configure NTLOADER configuration file
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Using a Windows Boot Loader to Dual Boot Linux (continued)
• Boot.ini: File used to configure NTLOADER
• For NTLOADER to be able to boot Linux, must specify the path to linboot.bin
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Using a Windows Boot Loader to Dual Boot Linux (continued)
Figure 9-8: NTLOADER operating system choice screen at boot time
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Linux Initialization
• Kernel assumes control after Linux loaded– Executes first daemon process (init daemon)
• /etc/inittab: Configuration file for init daemon
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Runlevels
• Runlevel: Defines number and type of daemons loaded into memory and executed– init daemon responsible for changing runlevels
• Often called initstates
• runlevel command: Displays current and most recent runlevel
• init command: Change OS runlevel
• telinit command: Alias to init command
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The /etc/inittab File
• Consulted to start or stop daemons
• /etc/rc.d/rc.sysinit: First script executed during system startup– Init hardware, set variables, check filesystems,
perform system tasks for daemon loading
• mingetty program: Displays login prompt on character-based terminals
• /etc/rc.d/rc.local file: Performs post-system-startup tasks
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The /etc/inittab File (continued)
• /etc/rc.d/rc command: Executes all files starting with S or K in /etc/rc.d/rc*.d/– Runlevel must be specified
• e.g., /etc/rc.d/rc 5 will execute files in /etc/rc.d/rc5.d/
– Symbolic links to scripts that start daemons– S means “Start,” K means “Kill”
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The /etc/inittab File (continued)
Figure 9-9: The Linux initialization process
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Configuring Daemon Startup
• Most symbolic links in /etc/rc.d/rc*.d point to daemon executable files in /etc/rc.d/init.d
• Most daemons accept arguments start, stop, restart
• To add daemons to be automatically started:– Add executable to /etc/rc.d/init.d– Create appropriate links to /etc/rc.d/rc*.d
• ntsysv utility: Modifies file entries in /etc/rc.d/rc*.d directories
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Configuring Daemon Startup (continued)
Figure 9-10: Results of ntsysv―level 5 command
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The X Windows System: Linux GUI Components
Figure 9-11: Components of the Linux GUI
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X Windows
• X Windows: Core component of Linux GUI
• X client: Requests graphics from X server and displays them– Does not need to run on same computer as X
Windows
• X server: Draws graphics
• XFree86: OSS version of X Windows– Originally intended for Intelx86 platform
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Windows Managers and Desktop Environments
• Window manager: Modifies look and feel of X Windows
• Desktop environment: Works with a window manager to provide standard GUI environment– Uses standard programs and development tools– KDE and GNOME are most common
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Windows Managers and Desktop Environments (continued)
• K Windows Manager (kwm): Window manager that works under KDE
• Qt toolkit: Software toolkit used with KDE
• GNOME Desktop Environment: Default desktop environment in Red Hat Linux– Sawfish Window Manager – GTK+ toolkit
• Xfce Desktop Environment: Consumes less hardware resources than KDE or GNOME
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Windows Managers and Desktop Environments (continued)
Figure 9-12: The KDE desktop
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Windows Managers and Desktop Environments (continued)
Figure 9-13: The GNOME desktop
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Windows Managers and Desktop Environments (continued)
Figure 9-14: The Xfce desktop
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Windows Managers and Desktop Environments (continued)
Figure 9-15: The Tab Window Manager
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Starting and Stopping X Windows
• runlevel 5 starts gdm– Displays graphical login screen– Allows user to choose the desktop environment or
Window Manager
• /etc/X11/gdm/gdm.conf: Contains gdm configuration data
• For runlevel 3:– Start gdm manually– Or, use startx command
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Starting and Stopping X Windows (continued)
Figure 9-16: The GNOME Display Manager
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Starting and Stopping X Windows (continued)
• startx command: start X Windows and Window Manager or desktop environment specified in .Xclients file in home directory– Usually points to .Xclients-default file
• Edit .Xclients-defaults file to start other desktops or Window Managers on X Windows
• Desktop Switching Tool: Change settings used in the .Xclients-default file from KDE or GNOME
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Starting and Stopping X Windows (continued)
Figure 9-17: The Desktop Switching Tool
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Configuring X Windows
• X Windows interfaces with video hardware– Requires information regarding keyboard, mouse,
monitor, and video adapter card• Required video adapter card information:
– Model– Amount of RAM– Chipset
• Required monitor information:– Maximum resolution supported– Horizontal sync (hsync) range– Vertical sync (vsync) range
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Configuring X Windows (continued)
• Mouse, keyboard, monitor, and video adapter card information stored in a file– /etc/X11/xorg.conf: X.org implementation of X
Windows– /etc/X11/XF86Config: XFree86 implementation of X
Windows
• mouseconfig and system-config-mouse commands: Configure mouse
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Configuring X Windows (continued)
Figure 9-18: Mouse configuration using mouseconfig
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Configuring X Windows (continued)
• system-config-keyboard command: Configure keyboard
• system-config-display command: Configure video adapter card and monitor
• xvidtune utility: Fine-tune the vsync and hsync of the video card
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Configuring X Windows (continued)
Figure 9-19: Keyboard configuration using system-config-keyboard
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Configuring X Windows (continued)
Figure 9-20: Configuring resolution and color depth using system-config-display
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Configuring X Windows (continued)
Figure 9-21: Configuring video card and monitor hardware using system-config-display
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Configuring X Windows (continued)
Figure 9-23: The xvidtune utility